Pressure is growing on social networks to play a bigger role in finding and weeding out jihadists and others looking to recruit members and plot deadly attacks.

But it’s more complicated than it sounds: networks like Facebook and Twitter support free expression, and filtering our bad actors is challenging both from a technical and civil liberties perspective.

Still, US and European officials are pressing social media to do more following deadly attacks over the past few weeks in Paris and southern California which have been linked to supporters of the Islamic State organization.

A White House statement earlier this month called for “a dialogue” with Silicon Valley and others on the subject, saying more should be done “when the use of social media crosses the line between communication and active terrorist plotting.”

The European Commission has also called for dialogue with the major social media networks.

And France passed emergency measures that could shut down websites or social media accounts which encourage terrorist actions.

Concerns have been rising amid increased presence on social networks of radical groups that seek to recruit fighters and communicate for planning.

FBI Director James Comey said the Islamic State organization, also known by the acronym ISIL, “has persistently used the Internet to communicate, and its widespread reach through the Internet and social media is most concerning.”

Comey said that through social media, “the message of radicalization spreads faster than we imagined just a few years ago.”

In Congress, Senators Dianne Feinstein and Richard Burr proposed legislation to require online communications services to report potential terrorist activity.

“That information can be the key to identifying and stopping terrorist recruitment or a terrorist attack, but we need help from technology companies,” said Feinstein, from California.

But it remains to be seen how much can be done by networks designed for sharing updates and which have hundreds of millions of users. And some say even if they could help in the fight against radicalization, the civil liberties price would be too high.